The document EP 1419568 B1 describes an electric motor with a high IP-rating in which a motor housing is formed partially from the pot-type rotor (external rotor). A slot between the rotating external rotor and the other, axially abutting part of the motor housing, which among other things holds the motor electronics and is stationary (non-rotating), is sealed off against the penetration of moisture or other foreign material from the outside by means of a suitable rotary seal, which in particular is configured as a labyrinth seal. This assures the desired high IP rating. Because of the virtually closed and/or encapsulated motor housing this produces, the problem arises that the power range is limited by the motor heat produced during operation. The indicated document therefore describes special means for internal cooling by internal air mixing in the internal region between the stator and rotor. Toward this end, the known motor features on the one hand, axially between the stator and an abutting electronics housing opposite the rotor, an internal fan wheel (cooling wheel) as well as, on the other hand, axially between the stator and the rotor base, a further cooling wheel. The effect of these cooling wheels rotating with the rotor is limited, however, because this only produces air circulation within the encapsulated internal space of the motor with the purpose of bringing heated air more intensively to specific mechanical parts, as for example a stator bushing and/or the rotor bell, by means of which the heat is then to be guided to the outside. This heat removal, to be sure, at least in the case of the rotor bell, is not especially effective, because the normally used material (drawn steel or plastic), possesses a heat conductivity of λ<100 W/m·k.